Electronic – Question regarding use of low voltage high current outputs


I see every day high voltage, high current; high voltage, low current. I rarely see low voltage, high current; why?

I know that I can take a high voltage, high current signal, send it through a step-down transformer and theoretically get a low voltage high current (with the same power output, of course), but I never see this done.

Can someone give me a reason as to why I wouldn't want a low-voltage high-current scenario?

Best Answer

There's a perfect example of a low voltage, high current device: a welder. Voltage as low as a few tens of volts, currents over 100A. That's kiloWatts.
The reason you don't see the combination low voltage/high current that often is that it's a rather inefficient way to get the power required: you need thick cables to carry the high current. It's much more practical to run the 1.5kW water kettle on 230V AC, so that it only needs 6.5A, than to run it on 20V, where you would need a thick cable to carry the 75A. Remember that we get the high voltage of 230V/115V from the grid already.